Sidepipe Brackets - My attempt at avoiding cracks in bracket mounting flanges

[Gumball]

My attempt at avoiding cracks in the sidepipes at the bracket mounting flanges. This method combines a few other builders' ideas, including removing the chassis pivot mounting point and using steel bushed rubber hangers.

Here's what I did:

1) added 1" long x 3/8 o.d. - 1/4" i.d. bushings to the rubber hangers;
2) installed a 1/4" rivnut on driver and passenger sides of the 2x2 tube;
3) cut about 3" off of each FFR bracket;
4) slightly bent the passenger side bracket to align it with the 2x2 tube; and
5) used bolts without threads on the last inch to hold the rubber to the chassis and to the bracket (2"x1/4"-20 to chassis and 1.5"x1/4"-20 to the bracket).

Bushings in the rubber ensure that the bolts don't distort when torqued, while also allowing the rubber to retain it's full range of flex - liberally slathered with white lithium grease, too:

http://i845.photobucket.com/albums/ab15/CCRsAC/SidepipeBracketBushingwithSpacers_zpse971df73.jpg

Rivnut installed in 2x2 chassis tube. This was very easy to insert without the floor pans in place:

http://i845.photobucket.com/albums/ab15/CCRsAC/SidepipeRivnutInstalled_zpsde25a0e7.jpg

Overhead view of the passenger FFR bracket. It wasn't lining up parallel to the 2x2 tubing, so I put it on a piece of wood and then under the hydraulic press it went for just a little "shaping" to get it in line with the mounting point and take any unneeded stress off of the sidepipe flange:

http://i845.photobucket.com/albums/ab15/CCRsAC/PassSidepipeBracketBent_zpsc7be9795.jpg

The finished product:

http://i845.photobucket.com/albums/ab15/CCRsAC/SidepipeBracketDirectBehind_zps5e92d5ab.jpg

[RGHarvey]

Chris,

Thanks for the post - I hope to be putting my sidepipes on soon and like your approach. Regards,
Bob

[SCFFR]

Nice work Chris!
Ron

[Cobradavid]

Nice work and a good write-up!

You might consider removing one of the bolts on the side pipe flange. As the side pipe moves up and down, the mounting bracket pivots - rotating around the bolt in the 2x2. Looking at your last pic, imagine pushing the end of side pipe down about 4". As the mounting bracket pivots down, the two side pipe bolts travel in an arc. Since the bolts move in different arcs, they try to rotate the side pipe. Because the side pipe is firmly attached to the headers and can't rotate, the up-and-down motion puts stress on the weld.
If you remove one of the bolts, the up-and-down motion of the side pipe (and resulting pivoting of the support bracket) will not try to rotate the side pipe, so the weld doesn't get stressed as much.

David

[skullandbones]

Hi guys,

I'm curious about the support function of the bracket. If you take a bolt out of the side pipe flange with the original FFR bracket install instructions (which I did) I can see how the relief of stress on the side pipe flange is accomplished. However, if you take the bolt out with the above modification, I don't see how it will work as a support bracket any more. I understand that it should dampen the movement of the side pipe and act as a "shock absorber" of sorts but not supporting a portion of the weight. I guess a good experiment would be to disconnect the side pipe from the header to see if it held it up like it does with the original install. In other words, I think you need two points of support at one end or the other of the bracket as a limiter. Please don't take this wrong. I'd just like a clarification. Thank you, WEK.

[Gumball]

Hi guys,

I'm curious about the support function of the bracket. If you take a bolt out of the side pipe flange with the original FFR bracket install instructions (which I did) I can see how the relief of stress on the side pipe flange is accomplished. However, if you take the bolt out with the above modification, I don't see how it will work as a support bracket any more. I understand that it should dampen the movement of the side pipe and act as a "shock absorber" of sorts but not supporting a portion of the weight. I guess a good experiment would be to disconnect the side pipe from the header to see if it held it up like it does with the original install. In other words, I think you need two points of support at one end or the other of the bracket as a limiter. Please don't take this wrong. I'd just like a clarification. Thank you, WEK.

In my experimenting, I found that it was going to be an either-or proposition for me. Either I was going to use the FFR original type of mounting for the bracket to the chassis (i.e., the pivot and the rubber hanger combined) with only one bolt in the bracket to sidepipe flange or, alternatively, the mounting that I did. I liked the version I went with better because it allows the pipes to move up and down with the engine, but with no other stress or resistance than what the rubber hangers allow. The rubber hangers are mounted "neutral" in that I installed the sidepipes to the headers first, then marked, drilled, and installed the rubber hangers. The goal was to damp movement and slightly support the sidepipes, without having to resort to a rigid mount between the sidepipes and the chassis.

[bucketlist]

avoid the bracket welded to the sidepipe (the weld area is the weak spot) if you are running a heat sheild (it will cover the strap) you can use a stainless band clamp, use the strap bolt to bolt a L bracket to the frame using a rubber bushing to help with vibration, you can use 2 straps to distribute the support.

[skullandbones]

Gumball,

Wondered if you have thought ahead about any re-inforcement for the side pipe bracket. I was contemplating a plate with a slot allowing you to slide it over the side pipe bracket. It could be welded to the bracket and the larger plate would accommodate a large welded surface to spread the load. You could do it now or wait until you start seeing cracks around the side pipe bracket. I believe they fail sooner or later. Maybe not. Do you think your approach will solve the "cracking side pipe syndrome"? Thanks, WEK.

[Gumball]

Gumball,

Wondered if you have thought ahead about any re-inforcement for the side pipe bracket. I was contemplating a plate with a slot allowing you to slide it over the side pipe bracket. It could be welded to the bracket and the larger plate would accommodate a large welded surface to spread the load. You could do it now or wait until you start seeing cracks around the side pipe bracket. I believe they fail sooner or later. Maybe not. Do you think your approach will solve the "cracking side pipe syndrome"? Thanks, WEK.

I was originally thinking along those lines. But, after giving the welds a good going over and deciding on how I was going to do the hangers, I decided not to add any material. It would certainly have strentghened the area, but I dont' think it is necessary with this type of hanger arrangement. The was I have these installed, the pipes are securely held in place by the headers - the hangers are completely neutral until torque is applied by reving the engine or driveline lash - just watch the pipes bounce on a car that is doing a burnout. The rubber hangers are surprisingly compliant and give a good range of movement, but will damp those twists and bounces.

From everything I read about the cracking issue, it appears to come from problems associated with using the full FFR bracket with two mounts, one of which is firmly attached to the frame, or when the driver's side bracket contacts the bottom of the chassis as the engine torques up and to the right under acceleration.

I think this method will avoid the cracking, but time will tell.

[BEAR-AvHistory]

Two questions, it the bottom of the bracket above the 4" round tube, cant tell from the picture. What is the ride height of your car?

FWIW if I had that much air between the support piece & the square tube the car would ground on speed bumps. My chassis bottom is two stacked 2X4's from the floor